A successful implementation of lithium metal is required to meet the volumetric and gravimetric energy density requirements of portable electronics and electric vehicles of the future. The SOLBAT project has made a good progress in understanding the causes of dendrite formation and propagation at the Li-metal|SE interface. At the cathode, volume changes of active particles during charge/discharge make retention of intimate contact within the SE a significant problem. Currently, none of the identified SE candidates have the necessary combination of electrochemical stability, ionic conductivity and mechanical properties to address this issue. A hybrid solid-liquid electrolyte (HSE) cell in which a solid-protected anode is combined with a conventional liquid-filled porous cathode would represent a more readily implementable route to the practical implementation of metal anode batteries. A HSE, introduces a new solid/liquid interface, poorly investigated in the literature but often associated with high impedances.
In this project, the student will investigate the solid electrolyte-liquid electrolyte interface as a function of charge state, cycling, current density, temperature and pressure, using a range of techniques including electrochemical impedance spectroscopy (3 and 4 electrodes), Raman, AFM, XPS, morphology studies by FIB/plasma-SEM, sample thinning and TEM-EDX and contact angle measurements. We will prioritize solid-electrolytes with proven stability in contact with Li-metal and explore the effect of doping, grain size and surface roughness/morphology on the interfacial impedance. Strategies to mitigate high impedances, e.g. surface treatments and coatings will be investigated.
